1. Field of the Invention
The present invention relates to computer tomography, and in particular to a computer tomography system and a method for operating same.
2. Description of the Prior Art
A computer tomography signal processing system is described in U.S. Pat. No. 4,135,247 having an X-ray source and receiver, the X-ray source emitting a fan-shaped X-ray beam which is incident on an array of individual detectors comprising the receiver, each detector forming an electrical signal corresponding to the received radiation intensity as the X-ray source is rotated around an exposure subject for transradiating a layer of the subject in the X-ray beam plane from different directions. The processing circuitry to which the output signals of the individual detectors obtained from the different transradiation directions are supplied identifies the attentuation values of predetermined points in the transradiated plane of the subject, and includes an image reproduction means for pictoriallly reproducing the calculated attenuation values. The processing circuit also includes a convolution computer for the measured data derived from the detector signals and an image reconstruction computer for generating a visual image from the received data.
In the known system described above, the convoluted signals contain at least two noise components, i.e., fluctuations of the measured values due to the finite quantum number (quantum noise) and noise stemming from the measuring electronics (electronics noise). Each of these noise components behaves differently as a function of the signal amplitude, and may cause image artifacts.